Telephone system



' Oct. 19, 1937.

R. F. MASSONNEAU TELEPHONE SYSTEM Filed July 11, 1935 INVENTOR By R./' .MA$$0NNEAU ATTORNEY SNEZE h vw mw F l J \Q T rs \N JHF +8 t 3 Patented Oct. 19, 1937 PATENT OFFlCE v TELEPHONE SYSTEM,

Robert F. Massonneau, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application Jul 11, 1935, Serial No. 30,800

6 Claims.

-' This invention relates to telephone systems and particularly to telephone systems arranged for metered service. g

The object of the invention is to provide a more I 5 reliable circuit arrangement for operating the meter of a calling subscriber in a measured service 'telephone system.

'In 7 telephone systems in which dial-impulse controlled selector, switches are employed in establishing connections between calling and called ;lines, it is usual to connect the meter of a measured service subscriber in parallel withthe line cut-off relay to the sleeve conductor of the-line, the ground potential, which is connected to this conductor upon extension of the line through a charging-trunk circuit arrangement to a first selector switch, being effective to operate the cutoff relay without. operating the meter. Thereafter, upon answer of a called station, a boosterbattery is temporarily connected to this sleeve conductor to operate the marginal meter, the cut-off relay being held operated. In case the charge to be made for a completed call depends upon the duration or destination of a call, or on both the duration and the destination, more than one operationof the meter may be required to charge for a particular call, the booster-battery being, in such a case, alternately connected to and disconnected from the sleeve conductor the required. number of times for the purpose of operating the meter'a corresponding number-of times.v The holding ground potential is reconnected to thesleeve conductor upon each disconnection of the booster-battery so that the cut-ofi relay is continuously held operated and the line is guarded against conversion to a second charging trunk and against seizure on an incoming call; but difliculty has been experienced in obtaining a meterwwhich will not operate when 40 ground potential is first connected to the sleeve conductor, which will operate when booster-battery is connected to the sleeve conductor, and which is certain to release when the holding and guarding ground potential is reconnected to the sleeve conductor; It is not practicable to employ a'booster-battery of higher potential than that which is within the usual marginof safety with and guarding ground potential connected to this conductor upon establishment of a connection originating over this line being effective to operate the cut-off relay without operating the meter; in which booster-:battery is connected to the sleeve conductor in place of the holding ground potential to operate the meter andlhold the cut-off relay; and in which, upon disconnection of thebooster-battery potential, the minimum potential required for holding the cut-01f relay operated is connected to the sleeve conductorfor a short interval of time to eiiect the 'release of the meter, the usual holding ground potential being thereupon reconnected to hold the cut-off relay operated without reoperating the meter.

This invention will be readily understood by considering a specific embodiment. A telephone system in which means are providedfor operating the meter of ,a subscribers station in accordance with the features of this invention is shown schematically in the drawing which forms a part of this specification.v The invention is not, however, limited in its application to the particular system shown but is, in general, applicable to all measured service telephone systems.

Referring to the drawing, A represents a subscribers station connected by a line Ll to terminals in the bank of a line-finder switch LF, CT represents a charging trunk through which the brushes of line-finder LF are permanently connected to a first selector S, Cl and C2 represent connector switches having access to subscribers lines for use in completing connections with called lines, and B represents a subscribers station connected by a line L2 to terminals in the bank of connector switch CI. The apparatus at each of stations A and B is of the type usually employed in automatic telephone systems and includes a dial for use in completing desired connections, Individual to the line Ll is the 'line relay I5, cut-off relay l6 and message register I]. The corresponding apparatus associated with line L2 is not shown. The line-finder switch LF, selector switch S and connector switches Cl and C2 are of the well-known two-motion stepby-step type. For a description of such switches and their operation when used as selector and connector switches reference may be had to pages 53 to 6'7 inclusive of the second edition of Automatic Telephony by Smith and Campbell. For a description of the operation of such a switch when used as a line-finder reference may be had to Patent No. 1,799,654 granted to R. L. Stokely, April 7, 1931. I The line-finder switch LF, selector Sand connector switch C2 are each represented.

12,3 as hereinafter'described, Relay :I6 locks by a set of brushes and a single setof terminals, the dotted lines leading tothe brushes representing the associated apparatus which is not shown. The connector Cl is represented by a set of brushes and one set of terminalsand by relays 44, 45 and 46; other associated apparatus, which is not shown, is represented by the broken lines leading to the brushes. The'charging trunk CT includes a supervisory relay 24 having its windings connected in series with talking conductors 2| and '22, relays 25, 26, 21 and 28, a'sourceof. booster-battery 30, a source ofbattery 3| which is of the. same polarity but lower in'potential than the regular central officfe battery which'is; shown connected to each-of the relays, interrupters 35, 36 and 31, and a'time-op-er'ated switching mechanism comprising the contacts 39 and electromagnet 38. The contacts of interrupter 35 are closed once every six seconds, the duration vo-f closure.being.a quarterofasecond; The contacts of both of interrupters 36 and 3'! areclosed once every two seconds, the duration ofclosnre .beinga quarter of a second; but the closure of .theflcontacts of interrupter 31 .does not begin viuntil about artwentieth of .a second before the closure of .the contactsof interrupter 36 ends.

'Each'closure of-interrupter 35 coincides with' everythird ..closure of interrupter 36. Each op- .eration of the inagnet'38 rotates the cam shaft one step, atotal of sixty steps constituting one revolution. The contact springs .39 are in the position shown only while the'shaft and camare Iin normal-position. v.

'IheinventionlwiH e further explained by-as 'suming a call to have been originated at station A, station B being the called station. Upon-remqVa1'-,0f the receiver (-not shown) at station" A, the line relay-.l'iisoperated by the energization 40 ,of its windings in 1a .circuit which includes the back contacts .ofrelay 1 6 and the conductors of lineLl; Relay l5 closes acircuit over-conductor .18 vforstartingan idle line-finder which in this case will be assumed to be the .line-finder -LF. Relay .1.5 also connects-the windings of-the'cutoff relay .l6 and service meter H, in" parallel,

gthrough theright hand front contact of relay 15,

through its right-hand front contact over con cluster 13 and at itsbackcontacts opens'the circuit for operating relay-:l5. The closing of the circuit through-brush 20 and the winding of relay] I6 is efifective tocause the brushes of "switchLF to stop on the setof terminals'to whichcondnctors I I, 1.2 and I 3 areconnected, thereby extendingythe line Ll over conductors '2"! and 22 'to the line relay (not shownlof selector S. Dial tone is thereupon transmitted to the calling station in usualmanner. When the calling subscriber .dials the number of the station with whichconnection is desired, the selector S and a connector CI are selectively operated in accordance with the digits dialedsAlthough not'shown other selectors might be included between the'selector' and. connector j Uponremoval of the receiver absence CI. Relay 44 of connector Cl is the line relay which responds to dial impulses, created by the dialing of the last two digits of the called subscribers number, to control the operation of the vertical and rotary: steppingimagnets which are not shown. The operation of relay 44, upon exand' [2, over conductors Zl and 22, and over conductors 4| and to the windings of relay 44, causes theoperation of the "release relay 45. Re-

lay 45, in operating, connects holding ground, .potentialthrough its front contact over conduce V tension of the connection from line conductors H i tor 43 through brush 46 of selector S, conductor j 33 of, the charging trunk CT, back contact of re-,

lay 28, right back contact of relay 21, sleeve conductor 23jbrush 20 of line-finder LF, conductor I3, and the front contact of cut-off relay I6 to the windings of relay l6 and service meter ll. 7 V

This holding ground potentialis effective to hold relay 1-6 operatedand to maintain theselector S scriber. The windings' of the polarized; supervisory .relay.24of charging trunk'QT are energized by the current overconductors 2! and 22 When the connector Cl establishes connection with the terminals ,to which'the; line 2 is con-1 l nected, :the line is tested and, if line L2 is idle;

ringing currentis transmitted through the brushes ofthe connector CI to operate the ringer atthe called station B.

hook at station 13 to ans-werthe call, relay 46 is operated, the connections between-conductors 4| -and ll-and the windings of relay' lft being thereby reversed to" cause the operation of; the polarized supervisory relay 24 of the charging trunk-QT.

The interrupting device 36 is arranged to close ZOI l and line-finderLF in their operated positionsrun .til the connectionis released by the callingsub- 51 fwhile the connection is being established, but 7 this current is notfin the'operating direction.

frornthe receiver'f its associated setgof contact springs for a half I second-once every six seconds and, as soon-as these contactsiareynext closed after the operation .of polarized relay-24,-relay26 isoperated' by the current-in a circuit from battery through its :right winding, contacts of relay -24, inner left. back contactof relay 26,-back contact ofirelay 25,-

' upper contact of springs 3910f timing mechanism T,'to ground atthe'lower contact of interrupter 36. Relay ;26 is only partially energized, by the current through-its right winding,,so as to close its right front contact without-affecting the left contacts. battery through the right winding of relay 26, front contact of relay 24-, left winding of relay 26,

' right front contact of relay 26, over'conductor 33 A circuit may then; be'trace'dfrom:

through brush 4D of selector S, conductor 430i a connector Cl to-ground at'the release relay-45.

Aslong as thelower contacts of interrupter 36 7 remain closed, the left winding- 10f relay 26 is short-circuited; but as soon' ast-he contacts of interrupter 36 are'openedybothwindings of relay 26 are energized inseries in the circuit over sleeve conductor 33 to cause the completefoperation of relay 26. ated until the contacts of interrupter 33 are next If the'polarized relay 2 4-remains'-oper.

.closed,.relay 2"! is then operated by thecurrent in .a circuit from'battery through its winding, the' inner left front contact of *re1ay,26, the right back contact of relay 25, the upper contacts of springs g I 39 of timing. mechanism'T to ground at the lower contacts of, interrupter 36.

In operating, relay" 21 connects booster battery through its inner; right :front contact, over sleeve conductor" 23,

brush 20, conductor 13 and the frontacontact of cut-offrelay Hi to the windings of the cut-off relay l6 and meter H to cause the operation of meter without releasing relay |6. Relay 2! also closes at its outer left front contact a circuit for operating the stepping magnet 38 of timing mechanism T. The operation of magnet 38 advances the timing mechanism T one step thereby moving the contact springs 39 out of normal position to close a circuit through the outer left front contact of relay 26, for operating relay 25. Relay 26 is effective, in combination with interrupter 36, to prevent the closing of the meter operating circuit and the advance of the timing mechanism T out of normal position in case supervisory relay 24 is only momentarily operated by a reversal of current due to the called line being busy. With relay 25 operated, the release of supervisory relay 24 is ineffective to cause the release of relay 26. Relay 2'! is held operated through its inner left front contact and the upper contacts of interrupter 36 until the interrupter contacts are again opened, the meter operating circuit beingthereby maintainedfor a long enough time to insure operation of meter Just before the opening of the contacts of interrupter 36, the closure of the contacts of interrupter 31 causes the operation of relay 28. When the contacts of interrupter 36 are opened, relay 2'! releases but relay 28 is held operated through its left front contact until the contacts of interrupter 31 are opened. The release of relay 21 causes the release of magnet 38 of timing mechanism T and connects magnet 38 to the contacts of interrupter 35 which are then open and which will not again be closed for approximately six seconds. The

release of relay 2'! disconnects sleeve conductor 23 from booster-battery 30 and connects conductor 23, through the right front contact of relay 28 to battery 3| thereby reducing the current through the windings of cut-off relay 5 and meter sufficiently to cause release of meter without releasing relay I6. When the contacts of interrupter 31 are opened, relay 28 releases, the sleeve conductor 23 being thereby disconnected from battery 3| and reconnected over sleeve conductor 33 to the usual holding and busy ground potential. The next succeeding closure of the contacts of interrupter 35 completes a circuit through the left back contact of relay 21 and inner left'front contact of relay 25 for operating magnet 38. The energization of magnet 38, once every six seconds, by the current in this circuit advances the shaft of timing mechanism T, step-by-step. The fifty-ninth closure of the contacts of interrupter 35, after relay 21 releases, completes an interval of six minutes which it is assumed is the unit for which there is a charge of one meter operation, the timing mechanism having completed one revolution.

Upon the shaft of timing mechanism T reaching normal, the contact springs 39 resume their normal position. Relay 25 is held operated, through its right front contact and the upper contacts of springs 39 until the contacts of interrupter 36 are opened. If supervisory relay connected to busy and holding ground potential when relay 28 releases. Thus the charging and timing cycle of operations is repeated once every six minutes as long as supervisory relay 24 remains operated. A temporary replacement of the receiver on the receiver-hook at the called station is eifective to stop further charging and the further advance of timing mechanism T as soon as it next reaches normal. Charging and timing would be resumed if the receiver were again removed at the called station before the connection were released by the calling subscriber.

When the receiver is replaced on the receiverhook at the calling station, the line relay 44 of connector C| releases followed by the release of relay 45. With both of relays 45 and 46 released, the connector Cl is restored to normal in usual manner. When relay 45 releases, holding ground potential is disconnected from conductors 43, 33, 23, and I3 thereby causing the release of cut-off relay l6 and the return of the line finder LF, selector S, and any other selectors involved in the connection, to normal in usual manner. Relay 26 releases when the holding ground potential is disconnected from conductor 33 and, if the timing mechanism '1' is not then normal and the contacts of interrupter 36 closed, causes the release of relay 25. If the timing mechanism is not normal, the release of relay 26 closes a circuit from battery through the winding and interrupter contacts of magnet 38, outer left back contact of relay 26 to ground at the middle contact of springs 39. The magnet 38 is thus alternately operated and released in rapid succession until the shaft of the timing switch reaches normal position.

A resistor may be substituted for battery 3| to temporarily reduce the current through the windings of relay I6 and meter sufficiently to cause releaseof the meter without releasing relay l6.

What is claimed is:

1. In a telephone system, a subscribers line, a relay and a meter connected in parallel to a conductor of said line, sources of potential, means for impressing a certain potential on said conductor sufficient to operate said relay but insufficient to operate said meter, means for changing the potential impressed on said conductor to operate said meter without releasing said relay, means for again changing the potential impressed on said conductor to release said meter without releasing said relay, and means for thereupon restoring the potential impressed on said conductor to said certain potential.

2. In a telephone system, a subscribers line, a relay and a meter connected in parallel to a conductor of said line, a first source of current capable of operating said relay but insufficient to operate said meter, a second source of current capable of holding said relay and of operating said meter, a third source of current capable of holding said relay operated but insufiicient to hold said meter operated, means for connecting said first source to said conductor, means for connecting said second source in place of said first source, and means for connecting said third source in place of said second source and for reconnecting said first source in place of said third source.

3. In a telephone system, a subscribers line, a relay and a meter connected in parallel to a conductor of said line, means for closing a first circuit over said conductor to operate said relay Without operating said meter, means for opening said first circuit and for closing a second circuit over said conductor to operate said meter and line cut-off relay and a meter connected in parallel to a control conductor of said line, means including a charging trunk for completing calls originating over said line, a first control relay, means comprising said control conductor and normally closed contacts of said first control relay for operating said cut-ofi relay without operating said meter, means comprising said control conductor and normally open contacts of said first control relay for operating said meter without releasing said cut-off relay, a second control relay, and means comprising said control conductor and said normally closed contacts of said first control relay and normally open contacts of said second control relay for causing the release of said meter Without releasing said cut-off relay.

5. In a telephone system, a calling subscribers line, a called subscribers line, a central-office battery having one pole grounded, a line cut-off relay and a meter connected in parallel between the non-grounded pole of said battery and a control conductor of said line, means including a charging trunk for completing a talking connection between said lines, a first control relay and a second control relay for said trunk, means comprising the normally closed contacts of continuity springs of said control relays for connecting ground potential to said control conductor, the

connection of ground potential to said conductor being indicative of the busy condition of said calling line and efiective to cause the operation of said cut-ofi relay but ineffective to cause the operation of said meter, abooster-battery, means comprising said continuityspring of the first control relay for connecting thebooster-battery to said control conductor in place of ground potential, a third battery having the same-pole connected to ground as does said central-ofiicebattery,vthe electromotive force of said third battery being less than that of said central-office battery, means comprising the normally closed contact of said continuity spring of the first control relay and the normally open contact'of said continuity to said control conductor in place of said boosterbattery, means responsive to the completion of said talking connection foroperating said first control relay and for holding said first control relay operated for a long enough interval of time to cause the operation of said meter, and means for operating said second control relay, after said first control relay has been operated long enough to cause the operation of said meter but before ROBERT F. MAssonNi Au '15 spring of thesecond control relay 'for connecting the non-grounded pole of said third battery 

